JPS6162057A - Picture formation method - Google Patents

Abstract

PURPOSE:To improve fixability and releasability under low temperature by forming a toner image with a specific toner and heating and fixing the toner image by a heat roller provided with a specific coat layer on its surface. CONSTITUTION:A toner image is formed on a transfer material with toner obtained by containing a releasing agent consisting of wax containing at least 20wt% ester component and having <=4 penetration and other necessary components in binder resin. Then, the toner image is fixed by a heat roller/fixer provided with a heat roller forming a coat layer having hardness corresponding to HB pencil hardness on its surface. Consequently, the fixing and releasing properties are sufficiently held even at a low temperature and transfer paper is prevented from being wound up even when picture formation is repeated continuously at a high speed, so that fine pictures can be stably and continuously formed many times.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is an image forming method in which an electrostatic charge image, a magnetic latent image, or the like is visualized with a toner, and the toner image formed thereby is transferred to a transfer paper or the like to obtain an image. This relates to a forming method.

[Prior art]

For example, an image forming method using electrophotography includes a step of forming an electrostatic image on a photosensitive drum, a developing step of visualizing this electrostatic image with toner to form a layer, and a step of converting this toner image into a layer. In the fixing step, the toner image formed in the developing step may be fixed to the support as is, but usually it is transferred to another support such as transfer paper and then fixed. I have to. Various methods are known for fixing toner images, but the contact heating fixing method using a heat roller is particularly superior in terms of high thermal efficiency, and is capable of high-speed fixing. Suitable for fixing in copying machines.

However, in recent years, there has been a strong demand for even higher speeds, and in order to achieve this, it is essential to increase the speed of toner image fixing.

Therefore, in order to fix toner images at high speed in the hot roller fixing method, the toner used for development is required to have good low-temperature fixability, and for this purpose, the binder resin that makes up the toner needs to be softened. Need to lower the score. However, if the softening point of the binder resin of the toner is lowered, the part of the toner that makes up the image will be transferred to the surface of the heat roller during fixing, and this will be transferred again to the transfer paper, etc. that is sent next. This tends to cause the so-called offset phenomenon, which contaminates the image. Furthermore, in the heat roller fixing method, in addition to the above-mentioned off-cent phenomenon, transfer paper, etc. may adhere to and wrap around the surface of the heat roller.
There is a problem that a so-called winding phenomenon occurs. This volume 4
The =J phenomenon occurs particularly when the temperature of the heat roller is too low.

In order to successfully achieve such high-speed fixing, the toner needs to be capable of low-temperature fixing and have excellent non-offset and non-rolling properties.

On the other hand, in a heat roller fixing device, a material with high mold releasability, such as perfluoroalkoxy (rl hereinafter abbreviated as FAJ), is coated on the surface of the heat roller. ) It is known to improve the releasability of the surface of the heat roller by providing a coating layer made of resin or the like. However, the commonly used P
The coating layer formed by FA resin has relatively low hardness,
Therefore, the surface of the heat roller is easily damaged by the separation claw for separating the transfer paper or the temperature sensor for temperature control, which are normally placed in contact with the heat roller.Especially in high-speed copying, in order to increase the rotational speed of the heat roller, the above-mentioned The occurrence of scratches like this becomes noticeable.

When scratches occur on the surface of the heat roller, the releasability of that area is significantly reduced, and this decrease cannot be compensated for by the releasability of the toner, which causes offset and wrapping phenomena. becomes.

For this reason, it is preferable that the coating layer provided on the surface of the heat roller has high hardness. The technology for forming a hard coating layer using PFA resin is as follows:
It is known to include metal powder such as chromium in PFA resin.

However, when the coating layer is formed using PFA resin containing metal powder, although the hardness is high and the durability is improved, the mold releasability of the metal powder-containing portion of the coating layer is low, resulting in the off-sen 1 phenomenon. Also, the occurrence of the winding phenomenon cannot be sufficiently prevented.

On the other hand, there is a known method for improving the non-wrapping property by incorporating a release agent made of a polyolefin wax such as polypropylene wax or polyethylene wax into the L-ner particles. .

However, in such a method, the non-volume (・1
In order to achieve a sufficient improvement in printability, the content of wax must be considerably increased, resulting in a decrease in the fluidity of the powdered toner, which ultimately impairs the developability and transferability. In addition, wax components may be mixed with the toner to form a two-component developer, such as a carrier, a developing sleeve, or an electrostatic image support. It has the disadvantage that it adheres and forms a film that causes staining, impeding its function. In addition, in a recycling system for efficient use of l-toner, that is, a system in which toner that has been used for development but has not been involved in the formation of a visible image is returned to the developing device and used again for development. The disadvantage is that the fluidity of the product is significantly reduced and the durability is low.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide sufficient fixing and releasing properties even at low temperatures, and to prevent the wrapping of transfer paper when forming images at high speed. An object of the present invention is to provide an image forming method that can stably form good images over a large number of times without causing any problems.

[Structure of the invention]

The above purpose is to add two ester components into the binder resin.
A toner image is formed using a toner containing a wax containing 0% by weight or more and a penetration rate of 4 or less, and the toner image is formed by a heated roller provided with a coating layer having a pencil hardness of H8 or more on the surface of the toner. This is achieved by an image forming method characterized by heat fixing.

The present invention will be explained in detail below.

In the present invention, a toner image is formed on a transfer material using a specific toner described in detail later, and a coating layer having a pencil hardness of HB or higher is provided on the surface of the toner image. The image is heat-fixed to form a copy image.

In the above, the transfer material may be any sheet material having the function of supporting the transferred toner image on its surface and fixing the toner image by a heating roller fixing device, such as paper, plastic sheet 1-1. Processed sheets etc. are available, and paper (transfer paper) is preferably used.

The toner used in the present invention contains, in a binder resin, a release agent made of wax containing at least 20% by weight of an ester component and having a lateral diameter of 4 or less, together with other necessary toner components. It is.

In the mold release agent, components other than the ester component may include higher fatty acids, higher alcohols, hydrocarbons, and the like.

A typical example of the release agent is carnauba wax. This carnauba wax is generally
The melting point is 78-86℃, and the alkyl ester of waxy acid is 8
0 to 85%, of which oxyacid esters account for about 70%.

In the above, the wax penetration is JIS K 223.
5-1980, based on the test method specified in 1980. That is, the sample wax was heated and melted, placed in a sample container, allowed to cool, and then kept at a constant temperature of 25°C in a constant temperature water bath. A needle with a total mass of 100 g is vertically advanced into the sample wax for 5 seconds, and the depth of penetration of the needle is measured to O.Imm, and the value obtained by multiplying this by 10 is defined as the penetration degree.

In the mold release agent, when the ester component is less than 20% by weight, the dispersibility in the binder resin is poor,
If sufficient mold release performance is not obtained during toner fixation, and if the penetration level exceeds 4, durability will be poor, and wax contamination will occur early, especially when used in a recycling system, resulting in a good product. It becomes difficult to carry out image processing.

Moreover, the melting point of the mold release agent is 60 to 110°C.
For example, the temperature is within the range of 160
Practically speaking, it is preferable that the melt viscosity at ℃ is 1 oocp or less. If the melting point is less than 60°C, the storage stability of the toner will decrease, and if the melting point exceeds 110°C, a sufficient release effect will not be obtained during low-temperature fixing. Further, when the melt viscosity exceeds 100 cp, toner fixation failure is likely to occur, and furthermore, a wrapping phenomenon is likely to occur.

The melting point of the wax is determined by differential scanning calorimetry (DSC). That is, the melting point is defined as the melting peak value when several samples are heated at a constant temperature increase rate (10°C/11in). Further, the melt viscosity of the wax can be measured using, for example, a B-type viscometer-1 (Tokyo Keiki Seisaku Kaisha).

Specific examples of the release agent include those listed in Table 1 below.

The content ratio of such a mold release agent is 1 to 1 to the binder resin.
Within the range of 20% by weight, preferably 1 to 10% by weight
is within the range of If this proportion is less than 1% by weight, the effect as a release agent is not exhibited, so the non-offset and non-wrapping properties of the toner are not improved, and the effect of lowering the minimum fixing temperature cannot be obtained. On the other hand, if it exceeds 20% by weight, the fluidity of the toner decreases, resulting in poor developability and transferability, making it impossible to form a good visible image, and also causing separation on the developing sleeve or electrostatic image support. The molding agent adheres and forms a film, which inhibits its function.

As the binder resin used in the toner in the present invention, various thermoplastic resins are used.

Specific examples include styrene compounds such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate. , ethyl methacrylate, n-butyl methacrylate, uryl methacrylate, α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; 2-vinylpyridine, 4 - Vinylpyridines such as vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone; Unsaturated carbonization of ethylene, propylene, isoprene, butadiene, etc. Polymers of monomers such as hydrogens and their halides, halogenated unsaturated hydrocarbons such as chloroprene, copolymers obtained by combining two or more of these monomers, and mixtures thereof, or Examples include non-vinyl condensation resins such as rosin-modified phenol-formalin resins, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, and polyether resins, or mixtures of these and the above-mentioned vinyl resins. Among these, styrenic resins containing high molecular weight components and low molecular weight components and having a ratio of weight average molecular weight Mw to number average molecular weight Mn (Mw/Mn) of 3.5 or more, chloroform insoluble content of 5% by weight or more The polyester resin is preferred because it has good fixing properties and non-rolling properties.

Examples of the 1-ner components used in the toner used in the present invention, if necessary, include colorants, magnetic materials, and various property improvers.

As a coloring agent, carbon black, nigrosine dye (
C, 1, No. 50415B), Aniline Blue (C,
I.

No. 50405), Calco Oil Blue (C, 1,
No, azoecBlue 3), Chrome Yellow (
C, 1, No, 14090), Ultramarine Blue (C, l No, 77103), DuPont Oil Red (C, 1, No, 26105), Quinoline Yellow (C
, 1, No. 47005), methylene blue chloride F (C, 1, No. 52015), phthalocyanine blue (C, I.

No. 74160), Malachite Green Off Sarate ((:, T, No. 42000), Lamp Black (C, r, No. 77266), Rose Bengal (C.
No. 45435), mixtures thereof, and others. These colorants need to be contained in a sufficient proportion to form a visible image with sufficient concentration, and are usually 1 to 2 parts by weight per 100 parts by weight of the binder resin.
0 parts by weight.

The magnetic material may be a metal or alloy that exhibits ferromagnetism such as ferrite, magnetite, iron, cobalt, or nickel, or a compound containing these elements, or a material that does not contain a ferromagnetic element but can be made by subjecting it to appropriate heat treatment. Mention may be made of alloys which become ferromagnetic, for example alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum, manganese-copper-tin, or chromium dioxide, among others. These magnetic substances are uniformly dispersed in the binder in the form of fine powder with an average particle size of 0.1 to 1 micron. And its content is toner 1
20 to 70 parts by weight per 00 parts by weight, preferably 40 to 7 parts by weight
It is 0 parts by weight.

Examples of the property improving agent include a charge control agent, an anti-offset agent, a lubricant for improving fluidity, and others.

The toner used in the present invention is mixed with a carrier made of iron powder, glass beads, etc. to make a two-component developer, but when it contains a magnetic material, it can be used as a one-component developer for developing electrostatic images. be done.

In the present invention, as described above, the l.color image is fixed using a heated roller fixing device equipped with a heated roller provided with a coating layer having a pencil hardness of IIB or higher on its surface. More preferably, the toner image is fixed using a heated roller fixing device having a heated roller provided with a coating layer having a pencil hardness of 111 or more on the surface thereof.

Hereinafter, pencil hardness refers to a value obtained in accordance with the test method specified in JIS K 5400.

If the pencil hardness of the coating layer is less than HB, the surface of the heat roller is likely to be scratched by the separation claw for separating the transfer paper or the temperature sensor for temperature control, and therefore the releasability of the surface of the heat roller may be affected. As a result, the winding phenomenon or offset phenomenon cannot be sufficiently prevented.

In the coating layer, the specific structure for making the pencil hardness equal to or higher than HB is not particularly limited, but for example, P
A coating layer made of FA resin containing metal powder such as chromium is preferred. With such a structure, it is possible to easily obtain a pencil hardness of 111 or more, and since the PFA resin provides good mold releasability, it is extremely practical. In this case, the content of the metal powder is, for example, 0.5 to 15% by weight based on the PFA resin, and the thickness of the coating layer is, for example, about 10 to 70 μm.

The heat roller having the coating layer as described above can be constructed by providing the coating layer on the surface of a cylindrical core made of aluminum or the like by an appropriate coating method, either directly or via an appropriate primer.

When this coating layer is formed by a coating method, it may be multilayered, for example, with two, three, four, or more layers, by overcoating.

The heat roller fixing device basically includes a heat roller, a backup roller that is in contact with the heat roller, and a heating mechanism for heating the heat roller, but its specific configuration is not particularly limited.

[Effects of the Invention] Since the present invention is an image forming method as described below, ζ has sufficient fixing and releasing properties at low temperatures, and when images are formed at high speed, transfer paper can be used easily. Winding occurs 4
First, good images can be stably formed many times.

Even when subjected to an image forming process using a recycling system, it has excellent durability and can stably form good images, and there is no contamination of the carrier, electrostatic image support, or developing sleeve by 1-ner. significantly smaller.

This effect can be obtained because the coating layer of the heat roller has a pencil hardness of 2" or higher, so even when the heat roller is rotated at high speed for high-speed copying, the heat roller is normally used. Scratches caused by foreign matter mixed into the thermal roller contact material brought in from the outside, such as the transfer pawl for the transfer paper, the temperature sensor for temperature control, or the transfer paper, which is placed in opposition to the transfer paper, are sufficiently prevented. Therefore, the releasability of the heat roller surface is stable over a long period of time, and even when the temperature of the heat roller drops considerably as image formation is continuously repeated at high speed, the release properties contained in the toner are maintained. Since the molding agent is made of wax containing an ester component of 20% by weight or more and a penetration of 4 or less, the wax has appropriate compatibility with the binder resin, and the wax is contained in the binder resin. It is contained in a fine and uniformly dispersed state, and therefore, even at low temperatures, the fine wax components melt sufficiently and ooze out over the entire surface of the toner, resulting in a good mold release effect even at low temperatures. Moreover, due to the melting of such wax, the melting temperature point of the binder resin of the toner shifts to the lower temperature side, and sufficient low-temperature fixability is exhibited, and the wax has a penetration of 4 or less. Since the toner itself is hard and highly durable, it can stably release the toner even when it is used in a recycling system, and the toner surface has high slipperiness, making it easy to fix. This is thought to be because it improves.

Since the adhesion of the toner to the heat roller is small, during fixing, the transfer paper does not move with the heat roller and is smoothly separated, so the transfer paper and heat roller are separated. Since the contact time is shortened and the amount of heat taken from the heat roller to the transfer paper is reduced, the effect of reducing the temperature drop of the heat roller during high-speed copying can also be obtained.

When the coating layer of the heat roller is formed by containing metal powder in PFA resin, the mold releasability of the metal powder-containing portion of the coating layer usually decreases;
- Since the toner has high mold releasability, such a decrease in mold releasability in the coating layer can be sufficiently compensated for by the toner,
As a result, an offset phenomenon and a wrapping phenomenon do not occur, and sufficiently good fixing can be achieved.

[Embodiments of the invention]

Examples of the present invention will be described below, but the present invention is not limited thereto. Note that "parts" represent parts by weight.

Example 1 (Production of binder resin) 299 g of terephthalic acid and polyoxypropylene (2,
2) 211 g of -2,2-bis(4-hydroxyphenyl)propane and 82 g of pentaerythritol were placed in a round tube equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a down-flow condenser. Place it in a bottom flask, set this flask on a mantle heater, introduce nitrogen gas from the nitrogen gas introduction tube to raise the temperature while keeping the inside of the flask in an inert atmosphere, and then add 0.05 g.
of dibutyltin oxide was added thereto, and the reaction was carried out at a temperature of 200°C while monitoring the reaction at the softening point to obtain a polyester resin having a chloroform insoluble content of 17% by weight and a softening point of 131'C. This is referred to as "Binder Resin AJ."

(Production of toner) Binder resin A 100 parts Mold release agent "Carnauba wax" (manufactured by Noda Wax Co., Ltd., ester component: 80-85% by weight, penetration: 1, melting point: 84°C) 3 parts Carbon blank [Mogul] A toner consisting of powder particles having an average particle size of 10 μm was obtained by kneading 10 parts or more of LJ (manufactured by Cabo Soto) using an extruder, cooling, pulverizing, and classifying.

Next, this l~lunar and a carrier made of iron powder coated with resin were mixed to prepare a developer having a toner concentration of 2% by weight.

Next, length 470mm, diameter 40mm, wall thickness 10mm
It has a recycling system for a fixing device comprising a heat roller made of a PFA resin containing chromium powder on the surface of an aluminum core metal, with a coating layer having a thickness of 35 μm and a pencil hardness of 111. Electrophotocopy machine
Attached to l-Bix 4500J (manufactured by Konishiroku Photo Industry Co., Ltd.), the linear speed of the heat roller was adjusted to 210 mm/see, and the above developer was used to develop the electrostatic image and transfer the toner image to transfer paper. Then, an actual photographic test was conducted using the process of fixing the toner image using a heat roller fixing device, and the temperature at which offset occurred and the temperature at which curling occurred were determined.

To measure the temperature at which Offsen 1 occurs, transfer the toner image.
The fixing process is performed by the above-mentioned fixing device, and then a blank transfer sheet is sent to the fixing device under the same conditions to observe whether or not toner stains occur on it. The temperature at which the offset occurred was determined by repeating the steps while increasing the temperature in sequence.

In addition, using a so-called rough black original, the operation of fixing toner on almost the entire surface of the transfer paper is carried out by sequentially lowering the set temperature of the heat roller of the fixing device in accordance with the measurement of the offset occurrence temperature described above. The coiling temperature was determined by repeating the test in this state.

The results are shown in Table 2.

Table 2 Also, when we conducted a continuous live-action test over 10,000 times, there were no scratches on the surface of the heat roller even after 100,000 times, and there was no winding phenomenon, so it remained in good condition until the end. It was possible to form images.

Example 2 In Example 1, [carnauba wax] was replaced with [
A developer was prepared in the same manner except that Candelilla Wax NO, IJ (manufactured by Noda Wax Co., Ltd., ester component = 24-30% by weight, penetration = 2, melting point: 64°C) was used, and the actual image was taken in the same manner. A test was conducted to determine the temperature at which offset occurs and the temperature at which winding occurs. The results are also shown in Table 2.

In addition, when we conducted a live-action test 100,000 times in a row, there were no scratches on the surface of the heat roller even after 100,000 times, and there was no wrapping phenomenon, and the image remained good until the end. I was able to perform the formation.

Comparative Example 1 In Example 1, “carnauba wax” was replaced with “
"Montan Wax" (manufactured by Hoechst Japan, ester component: 30-50% by weight, penetration: 8, melting point near 8℃)
) except that a developer was prepared in the same manner, and a photographic test was conducted in the same manner to determine the temperature at which offset occurs and the temperature at which curling occurs. The results are also shown in Table 2.

In addition, when we conducted a continuous live-action test for 100,000 times, there were no scratches on the surface of the heat roller even after 100,000 times, but there was early winding phenomenon and offset phenomenon. Image stains occurred.

Example 3 In the fixing device in Example 1, a thermal roller was formed by providing a coating layer made of PFA resin with a thickness of 35 μm and a pencil hardness of JIB on the surface of an aluminum core metal, but a photocopying process was carried out in the same manner as in Example 1. A test was conducted to determine the temperature at which offset occurs and the temperature at which winding occurs.

The results are also shown in Table 2.

In addition, when a live-action test was conducted continuously for 100,000 times, the results were good up to 50,000 times. However, after 50,000 cycles, scratches begin to appear on the surface of the heat roller, and after 60,000 cycles, image stains occur due to an offset phenomenon caused by scratches on the surface of the heat roller, and the winding (1-rolling phenomenon) occurs. occurred occasionally.

Procedural amendment (method) % formula % 1. Indication of the case Patent Application No. 183689 of 1983 2. Name of the invention Image forming method 3. Person making the amendment Relationship with the case Patent applicant address Nishi, Shinjuku-ku, Tokyo Shinjuku 1-26-2 Name (127) Roku Konishi Photo Industry Co., Ltd. 4, Agent 5, Date of amendment order (shipment date) January 29, 1985 6, Subject of amendment 1) Full text of specification 7 , Contents of amendment 1) As per the engraving and attached sheet of the specification originally attached to the application (no change in content)

Claims (1)

[Scope of Claims] 1) A toner image is formed using a toner containing a wax containing 20% by weight or more of an ester component and a penetration of 4 or less in a binder resin, and the surface thereof has a pencil hardness of H.
An image forming method characterized in that the toner image is heated and fixed by a heat roller provided with a coating layer of B or higher. 2) The image forming method according to claim 1, wherein the coating layer of the heat roller is made of perfluoroalkoxy resin containing metal powder.